The present invention refers to a sliding keel sailboat with a hull with reduced rolling.
As it is known, in the field of sailboats, different problems deriving from the sailing conditions and driving techniques exist. The present Applicant addressed efforts to solve at least two problems in particular, the first connected with the efficiency of the hull immersed in the water and the second connected with the comfort of the passengers during sailing.
In the standard sailboats, in which fittings and equipment are tightly bound to the hull, the action of the wind onto the sail surface gives rise to some forces which are transferred to the hull by a mast. Since the forces acting on the mast have a considerable lever arm in respect of the centre of gravity of the hull, it results a couple which tends to determine a certain roll angle, which angle is determined by the different forces at stake, weight and position of the crew aboard included.
The resulting attitude or roll angle in balance conditions, causes a twofold problem: from one hand, the so-called water lines of the hull are different from condition to condition, (continuously changing in compliance with the modification of the roll angle) and therefore they could not result appropriate in the specific state of sailing; from the other hand it results a heel attitude of the hull, to the point that the edges of the hull are partially immersed in the water or, even, the capsizing of the whole sailboat happens (which event, is not very appreciated by the inexperienced passengers which are aboard and also by the crew during the winter months).
But while the second problem has a minor importance—being connected with a general condition of “comfort”—the first one is of concern in all the sailboats where extra performances are required. In fact, if it is possible to design a hull provided to keep a constant attitude, it will also possible identify “water lines” extremely efficient without any sort of compromise, offering great advantages to the sailboat performance.
In the field, various attempts have been made to find an arrangement for the hull, equipment and rigging such to maintain the hull with a constant attitude, notwithstanding wind conditions.
Solutions which fores e to clear the mast from the hull by means of hinges or suitable kinematic chains, are among the most tested, but no one has had a convincing and satisfying practical application so far.
An example of said design, even if applied to a keel sailboat, consequently of big dimensions, is EP-A-375.637. Said document teaches to assembly a mast to a hull through a pin which allows the lateral swing of the mast. The mast crosses the hull in full and it is below linked to the mass of the keel, which keel also oscillates together with the mast. It is comprehensible how much such a solution is complex, both from the mechanical as well as the hydrodynamic point of view. Further, said solution has been only conceived for sailboats with big dimensions. Furthermore it is to be noted that having a deck plane completely stable, the acrobatic entertainment, often appreciated by the crew aboard, is absent.